Apparatus and method for regulating molten metal supply

ABSTRACT

Method and apparatus for maintenance of a controlled continuous feed supply of molten metal to a metallurgical plant. A supply ladle alternately feeds into one of two intermediate tipping vessels. The tipping of a first vessel is initiated when a predetermined degree of emptying of a second vessel is reached, and the flow of metal flowing from said second vessel is brought to a zero value at the appearance of metal flowing from said first vessel. Vessels in operative position are continuously weighed to generate a control signal for controlling their rate of tilting in order to obtain the desired feed supply.

'United States Patent Berthet et al.

APPARATUS AND METHOD FOR REGULATING MOLTEN METAL SUPPLY Inventors: Aristide Berthet; Jacques Blum,

both of Metz, France Institut De Recherches De La Siderurgie Francaise (IRSID), 78-St. Germain-en-laye, France Assignee:

Notice: The portion of the term of this patent subsequent to Nov. 20, 1990, has been disclaimed.

Filed: Aug. 22, 1974 App]. No.: 499,461

Related US. Application Data Continuation-impart of Ser. No. 413,662, Nov. 7, 1973, Pat. No. 3,856,182, which is a continuation-in-part of Ser. No. 230,746, March 1, 1972, Pat. No. 3,773,218.

Foreign Application Priority Data Mar. 2, 1971 France 71.07098 US. Cl. 222/1; 164/82; 164/155;

222/56 Int. Cl? B22D 37/00 Field of Search 222/1, 56, 58, DIG. 15;

[56] References Cited UNITED STATES PATENTS 2,905,989 9/1959 Black 164/155 3,457,985 7/1969 Wilson..... 164/155 3,599,835 8/1971 Kocks 222/58 3,772,455 12/1950 Easton et al. 222/56 UX 3,773,218 11/1973 Berthet et al. 222/] Primary ExaminerRobert B. Reeves Assistant Examiner-David A. Scherbel Attorney, Agent, or Firm-Burgess Ryan and Wayne [57] ABSTRACT Method and apparatus for maintenance of a controlled continuous feed supply of molten metal to a metallurgical plant. A supply ladle alternately feeds into one of two intermediate tipping vessels. The tipping of a first vessel is initiated when a predetermined degree of emptying of a second vessel is reached, and the flow of metal flowing from said second vessel is brought to a zero value at the appearance of metal flowing from vessel. Vessels in operative position are continuously weighed to generate a control signal for controlling their rate of tilting in order to obtain the desired :feed supply.

1'2 'Cfiims, 4 Drawing Figures MOTOR PUMP OFF on US. Patent Nov. 4, 1975 Sheet 1 of4 3,917,111

Sheet2 0'54 3,917,111

US. Patent Nov. 4, 1975 US. Patent Nov. 4, 1975 Sheet 3 of4 3,917,111

53m mohoi m QI mint mohoz wm nmw u JSPZmKuHEE Q zoEjRmm nkw U.S. Patent Nov. 4, 1975 Sheet 4 of4 3,917,111

1 APPARATUS AND METHOD FOR REGULATING MOLTEN METAL SUPPLY This application is a continuation-in-part of copending application Ser. No. 413,662 filed Nov. 7, 1973, now US. Pat. No. 3,856,182 which was a continuationin-part of application Ser. No. 230,746 filed Mar. 1, 1972 and now US. Pat. No. 3,773,218. According to the present invention, a method of supplying a controlled feed of metal to a metallurgical plant is provided from at least two intermediate tipping vessels, comprising tipping a filled intermediate vessel to obtaina flow of metal, continuously weighing the vessel as it is being tipped so as to determine the flow of metal running out of said vessel, comparing the flow of metal with a reference quantity representing a desired flow of metal, developing from the determined flow and the reference quantity 'a differential signal, adjusting the rate of tipping of the intermediate vessel while metal is running out therefrom so as to bring said differential signal back to a substantially zero value, stopping the tipping of the intermediate vessel while metal is running out therefrom, and initiating the tipping of another filled vessel when the first vessel from which metal is running out reaches a predetermined degree of emptying.

Preferably, the methodincludes detecting the apparance of flow of metal from the one vessel at the start of tipping, developing a singal at the moment when such flow of metal appears and initiating through this signal the elimination of the flow of metal from the other vessel at the end of tipping and the taking over by regulation equipment of the control of the rate of tipping of the one vessel at the start of tipping.

Alternatively, the method includes detecting the appearance of flow of metal from one of two intermediate vessels at the start of tipping, developing a signal at the instant such flow appears, and, by means of such signal, controlling stoppage of the tipping of the other vessel, the metal continuing to be emptied from the other vessel at a decreasing rate, initiating control by regulation equipment of the vessel at the start of tipping through summing the flows running out of thetwo intermediate vessels, and acting on the flow from the vessel controlled by the regulation-equipment so as to regulate the total flow.

Further, according to the present invention, apparatus is provided for supplying a controlled feed of metal to a metallurgical plant, comprising at least two intermediate tipping vessels, means for alternatively filling said vessels from said metal supplying means and emptying the vessels into said metallurgical equipment to obtain a continuous flow of molten metal; means for determining the actual flow of metal running out from the vessel being emptied; means for providing a reference quantity corresponding to .a desired constant supplying flow rate of molten metal; comparison means of developinga differential signal by comparing the actual flow rate and thedesired constant flow rate; regulating control means responsive to said differential signal for controlling the speed of tipping of each of said tipping vessels so as to maintain said differential signal ata sub.- stantially zero value; and cycling means for initiating alternatively the tipping of the vessel that is full when the vessel from which metal is running out reaches a.

predetermined degree of emptying then the return of the emptied vessel to its initial position.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a simplified plan view of a supply device which may be employed in accordance with the invention;

FIG. 2 is a simplified block diagram of a flow regulation in accordance with the invention;

FIG. 3 is a more complete block diagram of a flow regulation system in accordance with one embodiment of the invention; and

FIG. 4 is a more complete block diagram of a flow regulation system in accordance with another embodiment of the invention.

There is shown in FIG. 1, in a very simplified form,

one possible embodiment of a supply device comprising a primary ladle l which feeds two intermediate vessels 2 and 3. As shown, ladle 1 is located on a tipper and discharges into a runner conduit 4 whose directionof extension can be selected to enable supply of the metal to one or another of the intermediate vessels. In the situation shown, vessel 2 is in the process of being filled through conduit 4, and vessel 3 is in the process of emptying or discharging its supply of molten metal through a two-branched channel 5. It is to be understood that feed ladle .l is operable to fill intermediate vessels 2 and 3 alternately. In the embodimentshown, this switching of the direction of flow of the metal from ladle l is effected by swinging or pivoting conduit 4, but it could be achieved by displacement of the ladle while suspended on a crane, or by displacement of the ladle along rails. In order to maintain the regulation of the feed, vessels 2 and 3 are weighed as they discharge by known means (not shown), for example, by means of an extensometric-guage measuring bridge. Tipping'is effected, for example, by hydraulic jacks (not shown) which are so disposed that the value of their support re-. action does not interfere with the weighing of the vessels.

Reverting to FIG 1, it willbe understood that the continuity of the feed is insured by the alternate fillingup of one of the intermediate vessels and the tipping of the other during filling-up of the one. When supply ladle 1 is empty, it is replaced by another, the capacities of the three vessels being predetermined in order that this change-over, as well as the possible replacement of an intermediate vessel can be effected without interrupting the feed, i.e., during the; period of emptying of an intermediate vessel.

In order to ensure a desired flow of metal, the intermediate vessels are weighed at each instant in the course of emptying to determine the weight of metal emptied and derive the corresponding flow value. Then, in a regulator device, this flow value may be compared with a predetermined quantity correspond ing to a desired flow value, and the difference signal thus generated maybe used to actupon the tipping rate of the operative vessel to keep said difference signal substantially toa zero value.

When an intermediate vessel is almost empty, asignal, for example, a minimum weight reached, automatically initiates the tipping of the second intermediate vessel. This tipping is effected at high speeduntil the flow of metal is detected by suitable means such as photoelectric cells. For the next step, two manners of pro cedure may be considered.

In one of these, the excitation of the flow detection means causes, on the one hand, the stopping of the flow from the one intermediate vessel at the end of discharge, for example, by causing quick return to the initial disposition of this vessel, and on the other hand the taking over by the regulator of the control of the rate of tipping of the second vessel at this time. In this case there is therefore complete interruption in one metal flow and its replacement by another.

In the other procedure, the excitation of the flow detection means causes, on the one hand, stoppage of the tipping of the one vessel at the end of discharge while allowing the one vessel to discharge with a decreasing flow, and on the other hand, the taking over by the regulator of the control of the rate of tipping of the second vessel. For a few moments (up to stoppage of the flow of the first vessel), the regulation acts so that the sum of the two flows is equal to the reference flow.

Referring now to FIG. 2, a basic form of a regulation device in accordance with the invention will be described;

FIG. 2 diagrammatically represents the regulation circuit, said circuit beingseparated into two parts, the first of which, denoted by the reference numeral 6, insures the regulation; and the second of which, denoted by the reference numeral 7 insures the tipping of the intermediate vessel which is being regulated. A weighing meansS is provided for each vessel, so that there are as many weighing as there intermediate vessels. The weighing'means 8 constantly provides the weight of the vessels. The weighing means 8 constantly provides the weight of the vessels, these data being introduced into regulation part 6 through an analyzer 9 which provides a signal representing the weight of metal which has been emptied from the vessel during the course of emptying the vessel. Moreover, a reference quantity 10 is fed into a timer 1 1, said reference quantity corresponding to the desired flow value. The time 1 1 is therefore adapted to generate at each instant a value corresponding to the desired weight of metal to be fed to the metallurgical plant. Said desired weight value and weight of metal actually emptied are compared by means of a differential counter '12 which develops a differential signal that is then treated by a regulator 13 which supplies a voltage which, as can be seen, is added to the reference voltage at 14. This voltage is applied to the tipping ass'embly which comprises a variator 15 and a motor 16 which controls the tipping of an intermediate vessel 17. It will readily be understood that any difference in the measured flow of metal in relation to the reference quantity gives rise to an appropriate change in the supply voltage of motor 16 controlling the tipping so as to eliminate the recorded difference in flow. In the event of two flows of metal momentarily coexisting, the sum of the two is introduced into the regulation assembly and the flow is regulated by acting upon the flow of metal running out of the intermediate vessel at the start of tipping.

The analyzer 9 receives at its input an analog signal representing the weight of a vessel. There are as many analyzers 9 as there are intermediate vessels. Each analyzer 9 is adapted to deliver at its output a signal in binary notation, the magnitude of which represents the loss of weight Ap, if any, of the corresponding vessel. An analyzer may therefore comprise means for generating a numeric value corresponding to the difference between the weight of the vessel when full and the weight of the vessel at any instant or measurement. The coding into binary form may be readily obtained by means of a coder driven in a well-known manner by a 4 clock, the binary value being delivered at the frequency of the clock.

The timer 11 comprises a clock which delivers the time value t. Said timer is adapted to generate at its output a numeric signal in binary notation the magnitude of which corresponds to the instantaneous value of the product Q X t P where Q is a quantity representing the desired feed. This quantity is determined by a voltage applied to line 10, which in the specific case is a constant voltage corresponding to a constant flow rate of metal fed to the metallurgical equipment. It will be understood, of course, that the desired feed may be a time varying function, in which case a suitable time varying voltage is applied to line 10 to provide the desired controlled flow of metal.

The differential counter 12 forms the difference between the desired weight P and the loss of weight A, P,

said difference being either a positive or a negative number in binary notation. Said binary number is decoded and converted into an analog datum at the input of regulator 13, which is a conventional regulator, the output signal of which may be proportional to the input signal, but is generally further corrected by terms tak-.

ing into account the integral and the derivative of the input signal for the sake of stability of the regulation procedure. The output signal of regulator 13 is added to the reference voltage applied to line 10 by means of operational amplifier 14.

Since there is only one vessel at a time which stays under control of the regulation equipment, it is possible to make use of a system having a single variator 1,5, the switching of said variator to the adequate vessel occurring for example by means of hydraulic distributors.

ltwill be noted that this metal flow device and the regulation assembly is capable of operating whatever the shape of the intermediate vessels is, and that they enable compensation of any variation in their internal form which could occur through wearing of their refractories.

FIG. 3 illustrates an apparatus for regulating the flow according to the first procedure above described, in which the excitation of the flow detection means causes on the one hand the returning of the intermediate vesselat the end of discharge to the initial position of this vessel and on the other hand the taking over by the reg-. ulator of the control of the other vessel.

Referring to FIG. 3, there are shown weighing means 80, 8b for respectively weighing vessels 17a, 17b, sig nals corresponding to the measured weights being respectively applied to analyzers 9a, 9b which provide signals representing the weight of metal which has been emptied from the respective vessels. The reference voltage 10 is applied to time 11 which generates a signal corresponding to the weight of metal according to the desired feed. The desired weight value and the value of the weight of metal actually emptied are ap-, plied to differential counter 12 which delivers a differential signal treated by regulator 13 and added to the reference voltage 10 at 14. The resulting voltage is ap plied to variator 15 which controls the speed of motor 16 driving a pump 18, the pump being selectively connected to hydraulic jacks 28a, 28b for selectively controlling the rate of tipping of vessels 17a, 17b in a manner which will be further described herebelow.

The apparatus further comprises detection means for detecting the appearance of flow of metal from each vessel, said detection means consisting for example of photoelectric cells 26a, 26b respectively, arranged in the vicinity of the spouts of vessels 17a, 17b; comparison means 27a, 27b for comparing the measured weights with a predetermined minimum weight value Pm corresponding to a predetermined degree of emptying of the vessels; a high delivery pump driven by a motor 19 for selectively causing rapid tipping of the intermediate vessels 17a, 17b; and distributor relays 22a, 23a, 24a, a suitably actuated by the photoelectric cells 26a, 26b and the comparison means 27a, 27b in order to selectively connect each hydraulic jack either to pump 20, to pump 16, or to drain by way of distributors 22, 23, 24, 25 respectively so as to insure quick tipping of the corresponding vessel, then shifting of the tipping control to variator 15, then returning of the vessel to its initial position.

Each distributor is adapted to perform two functions corresponding to a so-called work position S and a rest position R. Actuating of each distributor is caused in a well-known manner by closing a contact in order to excite a solenoid; opening of said contact causes the distributor to return to its rest position R through action of a spring. The distributors may be conventional hydraulic valves.

The contact for exciting each solenoid is actuated by the relay having the same reference numeral as the distributor itself with the subscript 0 thus relay 22a when actuated causes distributor 22 to be set to its work position, etc.

Distributor 22 is adapted to selectively connect pump 18 to jacks 28a and 28b; distributor 23 is adapted to selectively connect pump 20 to jacks 28a and 28b; distributors 24 and 25 are respectively adapted to selectively connect jacks 28a or 28b to pump 18 or to drain through throttled ducts.

Motor 19 driving the pump 20 is started and stopped by means of a relay 21 actuated by the comparison means 27a, 27b in order to cause the starting of motor 19, and connected to the photoelectricc cells 26a, 26b in order to cause stopping of said motor. The operation of the apparatus will now be explained.

The initial tipping of a vessel, say vessel 17a, is caused by an operator by manually switching motors l6 and 19 on, the distributors being set in the following position: 22-R, 23-R, 24-S, 25-R. Oil from pump 20 flows through distributors 23 and 24 to jack 28a causing the rapid tipping of vessel 17a, and flows toward distributor 22 where it is blocked. Oil from pump 18 flows through distributor 22 toward distributors 23, 25, where it is blocked.

From then on, the operation is fully automatic. Photoelectric cells 26a detects the appearance of flow of metal from vessel 17a and causes the distributors 22 and 23 to switch to their work position S and simultaneously causes motor 19 to stop. Oil from pump 18 flows at a regulated rate of delivery through distributors 22 and 24 toward jack 28a and causes vessel 17a to be tipped at a tipping speed controlled by variator 15.

When the weight of vessel 17a reaches the predetermined minimum weight value Pm, comparison means 27a generates a signal which causes distributor 25 to be set at its work position S and simultaneously actuates relay 21 to start motor 19. This causes oil from pump 20 to flow through distributors 23 and 25 to jack 28b thus causing rapid tipping of vessel 17b. Oil flowing from pump 20 toward distributor 22 is blocked in said distributor. During the initial tipping of vessel 17b, the vessel 17a remains under the control of variator 15.

When the photoelectric cell 26b detects the appearance of the flow of metal from vessel 17b, it causes the distributors 22, 23 and 24 to switch back to their rest position R, and simultaneously causes motor 19 to stop. Rapid tipping of vessel 17b is discontinued and oil from pump 18 flows through distributors 22 and 25 toward jack 28b causing vessel 17b to be tipped at a tipping speed controlled by variator 15. Oil in jack 28a simultaneously escapes through distributor 24 to drain. the vessel 17a tilting back under its own weight to its initial position; the tilting back movement may be slowed down by throttling the escape duct.

When the weight of vessel 17b reaches the predetermined weight value Pm, comparison means 27b generates a signal which causes distributor 24 to be set at its work position Sand simultaneously actuates relay 21 to start motor 19. This causes oil from pump 20 to flow through distributors 23 and 24 to jack 28a thus causing rapid tipping of vessel 17a until photoelectric cell 2611 detects the appearance of flow of metal flowing from vessel 17a and causes the stopping of motor 19, the taking over by variator 15 of the control of the tipping speed of said vessel and the discharge to drain of oil in jack 28b, thus proceeding with the continuation of the operation as hereabove explained.

The value of the desired weight P transferred from clock 11 to counter 12 is reset to zero each time any of the photoelectric cells generates a signal at the appearance of flow of metal from a vessel at the start of tipping. This resetting to zero does not disturb the operation of the apparatus, since the desired flow of metal is determined by the voltage value 10.

The apparatus may further comprise memorizing means 19 which memorize the instantaneous value of the differential signal generated by the regulator 13. The value of saidsignal at the instant of switching of variator 15 from one vessel to the other vessel is caused to be transferred-at the input of said variator 15 by means of the signals generated by either of the two photoelectric cells 26a, 26b at the occurrence of metal flowing from said vessels. This permits the differential signal which is likely to exist at the instant when control of the tipping'sp eed of a vessel is switched to the other vessel to be t'ak'errinto account, thus enabling improved performance of the operation of regulating the feed to the metallurgical plant.

FIG. 4 illustrates an apparatus for regulating the flow of metal according to the second manner of procedure above discussed, in which the excitation of the flow detection meansca'uses on the one hand stoppage of the tipping of the vessel in the course of emptying, the metal continuing to be emptied from said vessel at a decreasing rate, and on the other hand initiates control by the regulation equipment of the vessel at the start of tipping by summing the flows running out of both intermediate vessels and acting on the rate of tipping of the vessel controlled by the regulation equipment so as to regulate the total -flow.

The apparatus of FIG.4 is substantially similar to the apparatus of FIG. 3 as regards the means for generating a control signal and the means for switching a high delivery pump or a control pump to either one of the jacks causing tipping of the vessels. The same reference numerals have therefore been used in FIG. 3 and FIG. 3 as far as the corresponding means remain identical and perform the same functions.

The two-function hydraulic distributors 24, 25 of FIG. 3 are replaced in FIG. 4 by three-function distributors 30, 31. The distributors 30, 31 are identical to each other and have two work positions which correspond to the two functions previously mentionedwith reference to distributors 24, 25, e.g. a first work posi-. tion S corresponding to the function performed by distributors 24, when set-in their work position S, and a second work position S corresponding to the function performed by distributors 24, 25when set in their rest position R. Each of the two distributors 30,31 is adapted to perform a third function corresponding to a rest position R, whereby a distributor is .setat a rest position by means of a spring (not shown) when said distributor is not set at one its two work:.postions S S Said third function corresponds to blocking a jack at any position. i

The apparatus of FIG. 4 further comprises two comparison circuits 32a, 32b respectively connected to the photoelectric cells 26a, 26b and which are adapted to generate a signal when there is no signal at the ouput of said photoelectric cells, e. g. when there is no metal running out of the corresponding vessel.

The distributor is set to its work position S by exciting asolenoid through 'a relay 301 actuated bycomparison means 27b. The relay 301 is also connected to the photoelectric cell 26bin order to cause de-excitation of the corresponding solenoid. The distributor 30 is set to its work position S by means of exciting a solenoid through a relay 302 actuated by the comparison circuit 32a. Relay 302 is also connected to the comparison means 27b in order to causede-excitation of the corresponding solenoid.

The distributor 31 .is similarly set to its work position S by means of a relay 31.1 connected to comparison means 27a. Relay 311 is also connected to the photoelectric cell 26a to cause -de-excitation of the corresponding solenoid. Distributor 31 is set to its work position S by means of a relay 312 connected to thecomparison circuit 32b, said relay being also connected to the comparison means 27a to cause de-excitation of the corresponding solenoid. The relays thusmay be bistable relays, or equivalent electronic devices.

The operation of theapparatus of FIG. 4 will be readily understood from the following explanation.

The initial tipping of a vessel, for example vessel 17a, is controlled by an operator by manually switching motors 16 and 19 on, the distributors being set-at the following positions: 22-R, 23-R, 30-S,, 3l-S Oil from pump 20 flows through distributors 23 and 30 to jack 28a causing quick tipping of vessel 17a, and flows toward distributor 22 where it is blocked. Oil from pump 18 flows through distributor 22 towarddistributor 31 where it is blocked. From then on the operation of the apparatus proceeds automatically.

Photoelectric cell 26a .detects the appearance of metal from vessel 17a and causes the distributors 22 and 23 to switch to their work position S and simultaneously casues motor 19 to stop. Oil from pump 18 flows at a regulated rate of delivery through distributors 22 and 30 to jack 28a and causes vessel 17a to be tipped at a tipping speed-controlled by variator 15.

When the weight of vessel 17a reaches the predetermined minimum weight value Pm, comparison means 27a generates a signal which causes distributor 31 to be set to its work position S and simultaneously actuates relay'2l to start motor 19. This causes oil from pump 20 to flow through distributors 23 and 31 to jack 28b, thuscausi ng rapidtipping of vessel-l7b. Oil flowing from pump 20 toward distributor 22 is blocked in said distributor. During the initial tipping of vessel 17b, vessel 17a remains under the control'of variator-15.

When the photoelectric cell-26b detects the appeari ance of the flow of metal from vessel 17b, this causes the distributors 22, 23, and 30 to switch to their respective rest positionsR-and simultaneously causes motor 19 to stop. Rapid tipping of vessel 17b is discontinued and oil from pump 18 flows through distributors 22 and 31 toward jack 28b causing vessel. 17b tobe tipped at a tipping speedcontrolled by variator 15.. Oil in jack 28a is blocked in distributor 30, the vessel 17a remaining in a tilted position corresponding to the position of said vessel at the instant of appearance of metal from vessel 17b. Thus the vessel 17a continues to be emptied but at a decreasing rate of emptying. Two signals corresponding to the respective values of the decreasein weight of vessels 17a and 17b are therefore introduced at the input of counter 12. The control signal at the input of variator 15 takes into account the sum of the flows running from both vessels and the rate of tipping of vessel 17 b is therefore controlled by variator 15 with the effect of regulating the total flow.

The signal generated by the photoelectric cell 2612 is also applied to clock 11 to reset to a zero value the value of the desired weight P, said desired value increasing again with a rate of increase fixed by the voltage value 10 in a similar manner as previously described with reference to FIG. 3. Moreover the differenttial signal generated by regulator 13 at the instant of discontinuing of the control of the rate of tipping of vessel 17a by variator 15 may be applied at the input of said variator at said instant through memorizing means 29, as it has been already explained with reference to FIG. 3. When metal running out of vessel 17a discontinues flowing the comparison circuit 32a generates a signal. which sets the distributor 30 to its work position S Oil in jack 28a escapes through distributor 30 to drain, the vessel 17a tilting back under its own weight to its initial untilted position where it may be refilled.

When the weight of the vessel 17b reaches the predetermined weight value Pm, comparison means 27b generates a signal which causes distributor 30 to be set at its work position S and simultaneously actuates relay 21 to start motor'19. This causes oil from pump 20 to flow through distributors 23 and 20 to jack 28a thus causing rapid tipping of vessel 17a, which has been refilled in the meanwhile, until the photoelectric cell 26a detects the appearance of the flow of metal flowing from vessel 17a and causes the stopping of motor 19, the setting of distributors 22 and 23 at theirwork position S, the setting of distributor 31' at its rest position R, and the resetting to a zero value of the value P generated by clock 11. The two vessels thus discharge simul taneously, vessel 17b emptying'at a decreasing rate and vessel 17a being tipped at a regulated-speed of tipping controlled by variatior 15, said variator receiving a control signal taking into account the sumof the flows running from both vessels. This procedure continues until the comparison circuit 32b generates a signal when metal stops flowing out of vessel 17b, said signal bringing distributor 31 to the work position S oil from jack 28b discharges to drain and the vessel 17b returns to its untilted position. The successive operations then proceed again as hereabove. described.

What is claimed is: k i

,1. A method of supplying a disired controlled flow of molten metal from at leasttwo intermediate tipping.

vessels provided with ;.-means controlling their rate of tipping, comprising tipping one of said vessels that is full to obtain a discharge flow of metal, continuously weighing said one vessel as it is being discharged so as to determine the flow of metal running out of said vessel, comparing said flow of metal with a time varying reference quantity representing the, desired flow of molten metal, developing from the comparison of determined flow and the reference quantity a differential signal corresponding to the difference in their values, modifying the tipping rate of said one vessel while metal is running out therefrom so as to bring said differential signal back to a substantially zero value, stopping the tipping of said one vessel while metal is running out therefrom, and initiating the tipping of the other vessel that is full when the one vessel from which metal is running out reaches a perdetermined degree of emptying.

2. A method of supplying a substantially constant flow of molten metal from at least two intermediate tipping vessels provided with means controlling their rate of tipping, comprising tipping one of said vessels that is full to obtain a discharge flow of metal, continuously weighing said one vessel as it is being discharged so as to determine the flow of metal running out of said vessel, comparing said flow of metal with a time varying reference quantity representing a constant flow of molten metal, developing from the comparison of determined flow and the reference quantity a differential signal corresponding to the difference in their values, modifying the tipping rate of said one vessel while metal is running out therefrom so as to bring said differential signal back to a substantially zero value, stopping the tipping of said one vessel while metal is running out therefrom, and initiating the tipping of the other vessel that is full when the one vessel from which metal is running out reaches a predetermined degree of emptying.

3. A method of supplying a disired controlled flow of molten metal from at least two intermediate tipping vessels provided with means controlling their rate of tipping, comprising tipping one of said vessels that is full to obtain a discharge flow of metal, weighing said one vessel as it is being discharged so as to determine the weight of metal which has run out of said vessel, comparing said weight of metal with a target weight derived from a time varying reference quantity corresponding to the desired flow rate, developing from said weight of metal and said target weight a differential signal corresponding to the difference in their values, modifying the tipping rate of said one vessel while metal is running out therefrom so as to bring said differential signal back to a substantially zero value, stopping the tipping of said one vessel while metal is running out therefrom, and initiating the tipping of the other vessel that is full when the one vessel from which metal is running out reaches a predetermined degree of emptying.

4. A method according to claim 1, including detecting the appearance of flow of metal from the one vessel at the start of tipping, developing a signal at the moment when such flow of metal appears, initiating through said signal the elimination of the flow of metal from the other vessel at the end of tipping and initiating through said signal the switching of the controlling means for regulating the rate of tipping from said other vessel to the one vessel at the start of tipping.

5. A method according to claim 1, including detecting the appearance of flow of metal from the one vessel at the start of tipping, developing a signal at the instant such flow appears, and by means of said signal, causing stoppage of the tipping of the other vessel, the metal continuing to be emptied from said other vessel at a decreasing rate, initiating the switching of the controlling means for regulating the rate of tipping from said other vessel to the one vessel at the start of tipping, and initiating the summation of the flows from the two vessels to develop the differential signal for regulating the rate of tipping of said one vessel.

6.-A method according to claim 1, in which the initiating of the tipping of a vessel is provided by a prede termined weight of the other vessel.

7. A method according to claim 1, in which the initiating of the tipping of a vessel is provided by a geometrical position of the other vessel.

8. An apparatus for supplying a desired controlled flow of molten metal from metal supplying means to a metallurgical equipment comprising:

at least two intermediate tipping vessels, means for alternatively filling said vessels from said metal supplying means and emptying the vessels into said metallurgical equipment to obtain a continuous flow of molten metal;

means for determining the actual flow of metal running out from the vessel being emptied;

means for providing a time varying reference quantity corresponding to the desired flow of molten metal; comparison means for developing a differential signal by comparing the actual flow and the desired flow;

regulating control means responsive to said differential signal for controlling the speed of tipping of each of said tipping vessels so as to maintain said differential signal at a substantially zero value; and

cycling means for initiating alternatively the tipping of the vessel that is full when the vessel from which metal is running out reaches a predetermined degree of emptying then the return of the emptied vessel to its initial position.

9. An apparatus for supplying a desired controlled flow of molten metal from metal supplying means to a metallurgical equipment comprising:

at least two intermediate tipping vessels, means for alternatively filling said vessels from said metal supplying means and emptying the vessels into said metallurgical equipment to obtain a continuous flow of molten metal;

means for determining the actual weight of metal which has run out from the vessel in the course of emptying;

means for providing a time varying reference quantity corresponding to the desired flow rate of molten metal;

means for developing from said reference quantity a target weight value;

comparison means for developing a differential signal by comparing the value of the actual weight of metal and the target weight-value; regulating control means responsive to said difierential signal for successively controlling the speed of tipping of said tipping vessels so as to maintain said differential signal at a substantially zero value;

and cycling means for initiating alternatively the tipping of the vessel that is full when the vessel from which metal is running out reaches a predetermined degree of emptying, then the return of the emptied vessel to its initial position.

10. An apparatus according to claim 9, including:

detection means for detecting the appearance of flow of metal from each vessel at the start of tipping said detection means developing a cycling signal at the moment when such flow of metal appears; and switching means responsive to said cycling signal for switching said regulating means controlling the speed of tipping from the vessel in the course of being emptied to the full vessel to be emptied. 11. An apparatus according to claim 10, in which there is an overlapping of metal flows from both vessels, including means responsive to said cycling signal for stopping the tipping of the emptied vessel, the metal continuing to flow out from this vessel at a decreasing rate at the appearance of flow of metal from the full 12. An apparatus according to claim 10, including memorizing means connected between said comparison means and said regulating means for memorizing the instantaneous value of the difierential signal, said memorizing means being also connected to the detection means in order to causer the instantaneous value of the differential signal to be transferred at the input of said regulating means when said detection means develop said cycling signal. 

1. A method of supplying a disired controlled flow of molten metal from at least two intermediate tipping vessels provided with means controlling their rate of tipping, comprising tipping one of said vessels that is full to obtain a discharge flow of metal, continuously weighing said one vessel as it is being discharged so as to determine the flow of metal running out of said vessel, comparing said flow of metal with a time varying reference quantity representing the desired flow of molten metal, developing from the comparison of determined flow and the reference quantity a differential signal corresponding to the difference in their values, modifying the tipping rate of said one vessel while metal is running out therefrom so as to bring said differential signal back to a substantially zero value, stopping the tipping of said one vessel while metal is running out therefrom, and initiating the tipping of the other vessel that is full when the one vessel from which metal is running out reaches a perdetermined degree of emptying.
 2. A method of supplying a substantially constant flow of molten metal from at least two intermediate tipping vessels provided with means controlling their rate of tipping, comprising tipping one of said vessels that is full to obtain a discharge flow of metal, continuously weighing said one vessel as it is being discharged so as to determine the flow of metAl running out of said vessel, comparing said flow of metal with a time varying reference quantity representing a constant flow of molten metal, developing from the comparison of determined flow and the reference quantity a differential signal corresponding to the difference in their values, modifying the tipping rate of said one vessel while metal is running out therefrom so as to bring said differential signal back to a substantially zero value, stopping the tipping of said one vessel while metal is running out therefrom, and initiating the tipping of the other vessel that is full when the one vessel from which metal is running out reaches a predetermined degree of emptying.
 3. A method of supplying a disired controlled flow of molten metal from at least two intermediate tipping vessels provided with means controlling their rate of tipping, comprising tipping one of said vessels that is full to obtain a discharge flow of metal, weighing said one vessel as it is being discharged so as to determine the weight of metal which has run out of said vessel, comparing said weight of metal with a target weight derived from a time varying reference quantity corresponding to the desired flow rate, developing from said weight of metal and said target weight a differential signal corresponding to the difference in their values, modifying the tipping rate of said one vessel while metal is running out therefrom so as to bring said differential signal back to a substantially zero value, stopping the tipping of said one vessel while metal is running out therefrom, and initiating the tipping of the other vessel that is full when the one vessel from which metal is running out reaches a predetermined degree of emptying.
 4. A method according to claim 1, including detecting the appearance of flow of metal from the one vessel at the start of tipping, developing a signal at the moment when such flow of metal appears, initiating through said signal the elimination of the flow of metal from the other vessel at the end of tipping and initiating through said signal the switching of the controlling means for regulating the rate of tipping from said other vessel to the one vessel at the start of tipping.
 5. A method according to claim 1, including detecting the appearance of flow of metal from the one vessel at the start of tipping, developing a signal at the instant such flow appears, and by means of said signal, causing stoppage of the tipping of the other vessel, the metal continuing to be emptied from said other vessel at a decreasing rate, initiating the switching of the controlling means for regulating the rate of tipping from said other vessel to the one vessel at the start of tipping, and initiating the summation of the flows from the two vessels to develop the differential signal for regulating the rate of tipping of said one vessel.
 6. A method according to claim 1, in which the initiating of the tipping of a vessel is provided by a predetermined weight of the other vessel.
 7. A method according to claim 1, in which the initiating of the tipping of a vessel is provided by a geometrical position of the other vessel.
 8. An apparatus for supplying a desired controlled flow of molten metal from metal supplying means to a metallurgical equipment comprising: at least two intermediate tipping vessels, means for alternatively filling said vessels from said metal supplying means and emptying the vessels into said metallurgical equipment to obtain a continuous flow of molten metal; means for determining the actual flow of metal running out from the vessel being emptied; means for providing a time varying reference quantity corresponding to the desired flow of molten metal; comparison means for developing a differential signal by comparing the actual flow and the desired flow; regulating control means responsive to said differential signal for controlling the speed of tipping of each of said tipping vessels so as to maintain said differential signal at a substaNtially zero value; and cycling means for initiating alternatively the tipping of the vessel that is full when the vessel from which metal is running out reaches a predetermined degree of emptying then the return of the emptied vessel to its initial position.
 9. An apparatus for supplying a desired controlled flow of molten metal from metal supplying means to a metallurgical equipment comprising: at least two intermediate tipping vessels, means for alternatively filling said vessels from said metal supplying means and emptying the vessels into said metallurgical equipment to obtain a continuous flow of molten metal; means for determining the actual weight of metal which has run out from the vessel in the course of emptying; means for providing a time varying reference quantity corresponding to the desired flow rate of molten metal; means for developing from said reference quantity a target weight value; comparison means for developing a differential signal by comparing the value of the actual weight of metal and the target weight-value; regulating control means responsive to said differential signal for successively controlling the speed of tipping of said tipping vessels so as to maintain said differential signal at a substantially zero value; and cycling means for initiating alternatively the tipping of the vessel that is full when the vessel from which metal is running out reaches a predetermined degree of emptying, then the return of the emptied vessel to its initial position.
 10. An apparatus according to claim 9, including: detection means for detecting the appearance of flow of metal from each vessel at the start of tipping, said detection means developing a cycling signal at the moment when such flow of metal appears; and switching means responsive to said cycling signal for switching said regulating means controlling the speed of tipping from the vessel in the course of being emptied to the full vessel to be emptied.
 11. An apparatus according to claim 10, in which there is an overlapping of metal flows from both vessels, including means responsive to said cycling signal for stopping the tipping of the emptied vessel, the metal continuing to flow out from this vessel at a decreasing rate at the appearance of flow of metal from the full vessel, said comparison means developing said differential signal by comparing the value of the sum of the weights to metal which have run out of the two vessels and the target-weight value.
 12. An apparatus according to claim 10, including memorizing means connected between said comparison means and said regulating means for memorizing the instantaneous value of the differential signal, said memorizing means being also connected to the detection means in order to causer the instantaneous value of the differential signal to be transferred at the input of said regulating means when said detection means develop said cycling signal. 